Vaillant ashp (my battle with).

[S2D2]

Assuming they are replacing with an Arotherm Plus, they have a rather odd step in the minimum system volume dependent on size.

 

10/12kW models: 150l

7kW: 55l

3.5/5kW: 40l

 

I've only just started looking at this but I doubt anyone is fitting a big enough buffer to hit 150l, so I would query this with them as it seems a massive jump from 55l to 150l. Getting down to a 7kW model might solve the headache if you can make up the system volume in the radiators/pipework.

 

You can also drastically reduce the required volume with the 6kW backup heater which is relatively small but will cost more to run, I have no idea how much it would come on for normal usage, I've only just seen that it exists. Including this changes the minimum volumes to:

 

10/12kW models: 45l

7kW: 20l

3.5/5kW: 15l

 

Which you should be able to hit with radiators alone. Information for the larger units here in appendix E: https://www.vaillant.co.uk/downloads/product-brochures/arotherm-plus-230v-double-2626669.pdf

[Beelbeebub]

How many litres of buffer/volumiser do you need?

 

Grant do a nice small unit, about 11liters (tho g on the left) 

 

If you already have an indoor hydro unit, you coiod replace that with 2 or 3 of those for 35l or so. It has an immersion backup as well. 

 

With regards to the buffer not being in the loft. If the only objection is "it needs to be in the insulated envelope" (which sounds like an excuse) then slapping an insulated box around it would be pretty easy.

 

Grant make a volumiser tank specifically for external mounting. 

 

 

 

[JohnMo]

Grant also do a two port one that is designed to be mounted outside on the ASHP feet. It has an immersion inside also.

 

Just read the last sentence in the above reply which says the same

Edited August 28, 2023 by JohnMo

[Marvin]

3 hours ago, zoothorn said:

A customer, consider old mrs. Miggins at no.73 for example, shouldn't be expected to have to consider engineering minutiae. Surely.

 Surely that is why the designer comes up with a the particular design for your home??

 

As I mentioned earlier:

 

17 hours ago, Marvin said:

Also I feel the most efficient installation would have the shortest pipe distance between the ASHP, the Hot Water tank and the Buffer tank and the report indicated that the hot water and Buffer tank should be within the building thermal envelope.

 

So I believe they are trying to give best advice. 

 

 

Again:

 

3 hours ago, zoothorn said:

Why the installer is so insistent, is beyond me. He even said at this August 22 visit "you could do without, but it's a compromise/ may not work as well/ possible guarantee compromised" (8 yrs.. this decent guarantee, for me alone here with a low income, I cannot compromise). 

 

As I commented earlier:

17 hours ago, Marvin said:

I think the understanding about the buffer tank usefulness is to do with the efficiencies achieved by the relationship between having small zoning demands and the negative effect this can have on the ASHP cycling efficiency:

 

The report also said that most housing stock has little room for the buffer tank.

 

Again

 

Good luck

 

M

[zoothorn]

3 hours ago, JohnMo said:

Not sure that would work really, the other heated areas heat would just leach into the unheated room, if the fire off making heating the whole building worse.

 

How long do you run the lounge rads for per day? The rads should be matched to the heat loss - no matter what the heat loss is.

 

Anyway it is so unlikely that any manufacturer would agree to a retrofit partial install - it's just a waste of time suggesting it. More stress when they say no!

Hi JM,

 

you might find this odd, but I have no interest in actually using the ASHP for C.heating. It's so ineffective, that I had to ask them how to increace the flow temp/ & some other temp, to even then just get 1 mildy warm room as a result: a room just built & bang up to date insulation (all signed of by BCO) = far too expensive to be useable here.

 

But I can't tell them this. Or they might say "well your house ain't suitable [it isn't] so our offer is rescinded".

 

I only agreed to the system, for a new boiler. No other reason whatsoever; I knew 100% contrary to what the Govt Grant chap told me, that this cottage -wouldn't ever- be warm with this system. No fkn way. "Oh you'll be cosy.." he said etc (he merely had a number/ criteria to fill to get his job done & I was simply a convenient house to call at). My boiler was mouse-ridden & decrepit you see, the whole cottage terribly in need of renovating etc. So how could I dismiss a chance of a free new boiler? If it had an ashp box & new rads too.. these would/ could only ever be superflous & unused.

 

So I don't use the ashp for heating! If it's so very expensive for such little gain, no sense at all. I use a tiny fan heater, & an oil filled rad in my bedroom. Freezing cottage, used to it, can't do anything about it. Even a bigass stove struggles to heat the main room, so i decamp to my garden cabin when very cold with it's diddy stove: I'm only ever warm in here! Potty.

 

Zh

[zoothorn]

@S2D2 Many thanks indeed for your numbers there. I understand the jump thing.

 

I can use your post here as 'ammunition' in my (gently gently) inquiry to Head Office about the overall size of system proposed. If ONLY I could get them to fit a 7kw one instead.. my troubles are finally at an end.

 

Ludicrous that I'll never use the ASHP for heating, gratingly ironic, but there we go/ can't tell them this.

 

 

[zoothorn]

53 minutes ago, Marvin said:

 Surely that is why the designer comes up with a the particular design for your home??

 

As I mentioned earlier:

 

 

So I believe they are trying to give best advice. 

 

 

Again:

 

 

As I commented earlier:

 

The report also said that most housing stock has little room for the buffer tank.

 

Again

 

Good luck

 

M

Hi Marvin,

 

thanks but unfortunately I'm unable to comprehend this degree of engineering, to make use of your info, to understand their thinking. 
 

As a customer I'm adamant I shouldn't be expected to have A-level (if not degree-standard) over-complicated central-heating system engineering comprehension. I should only be expected to dial in my times, turn on a hot tap. And monitor it for any "Maintenance" symbol, or leak. 
 

Btw what report are you referring to-? (Housing stock etc?)

Edited August 28, 2023 by zoothorn

[Marvin]

Hi @zoothorn This is the report, although I don't think it will help you understand. 

 

hot_water_cylinders_buffer_tanks_heat_pumps.pdf

 

[TonyT]

4 hours ago, zoothorn said:

Hi JM,

 

you might find this odd, but I have no interest in actually using the ASHP for C.heating. It's so ineffective, that I had to ask them how to increace the flow temp/ & some other temp, to even then just get 1 mildy warm room as a result: a room just built & bang up to date insulation (all signed of by BCO) = far too expensive to be useable here.

 

But I can't tell them this. Or they might say "well your house ain't suitable [it isn't] so our offer is rescinded".

 

I only agreed to the system, for a new boiler. No other reason whatsoever; I knew 100% contrary to what the Govt Grant chap told me, that this cottage -wouldn't ever- be warm with this system. No fkn way. "Oh you'll be cosy.." he said etc (he merely had a number/ criteria to fill to get his job done & I was simply a convenient house to call at). My boiler was mouse-ridden & decrepit you see, the whole cottage terribly in need of renovating etc. So how could I dismiss a chance of a free new boiler? If it had an ashp box & new rads too.. these would/ could only ever be superflous & unused.

 

So I don't use the ashp for heating! If it's so very expensive for such little gain, no sense at all. I use a tiny fan heater, & an oil filled rad in my bedroom. Freezing cottage, used to it, can't do anything about it. Even a bigass stove struggles to heat the main room, so i decamp to my garden cabin when very cold with it's diddy stove: I'm only ever warm in here! Potty.

 

Zh

 

this is why the heat loss calculation is so important

for any heating system

 

the ASHP is just a source of heat, like a wood burner, gas boiler, electric panel heater, if the heat loss advises you need 8kW of heat to maintain say 21 deg inside when it’s -3 outside  you need 8kW or more, by any combination of source..

 

 

Edited August 28, 2023 by TonyT

[TonyT]

If you don’t want to use it, just make sure the cylinder/tank has an immersion  that you can manually turn on/off for you hot water.. 

[zoothorn]

2 hours ago, Marvin said:

Hi @zoothorn This is the report, although I don't think it will help you understand. 

 

hot_water_cylinders_buffer_tanks_heat_pumps.pdf 2.58 MB · 12 downloads

 

Hi Marvin, really appreciated. I've started/ tried, but 1/10th in.. it's way over my head. I can't possibly cope with the complexity to glean anything of use from it.

 

Seems I'm not really getting anywhere here.

[zoothorn]

45 minutes ago, TonyT said:

If you don’t want to use it, just make sure the cylinder/tank has an immersion  that you can manually turn on/off for you hot water.. 

 

Hi TT. The using of it.. or not, is far from what I need to concentrate on, for now.

 

I'm simply at this stage, how I get past this buffer hurdle. 
 

---
 

Ok, I need to rewind a step. Can anyone tell me why my current 'split' ashp doesn't have a buffer, but the replacement 'monoblock' ashp (which is it safe to assume is the same kW figure?)........... does?

 

Thanks Zoot

Edited August 28, 2023 by zoothorn

[zoothorn]

And another question please chaps: I see some form of weird expansion white vessel/ tank, sitting atop the cylinder currently.

 

Is this a buffer??

[TonyT]

You need to supply photos, this was the issue before when we all tried to help…

 

Why not forget about the buffer when you don’t want to use it, forget about it and just use the immersion heater…

 

so learn about what you actually want to use.

 

[zoothorn]

52 minutes ago, TonyT said:

You need to supply photos, this was the issue before when we all tried to help…

 

Why not forget about the buffer when you don’t want to use it, forget about it and just use the immersion heater…

 

so learn about what you actually want to use.

 

Tony,

 

it's not to do with my using the ashp in any way. This is irrelevant (on this aspect anyway, as I've said- I won't use the C.heating).

 

I'm simply at the stumbling block of siting this wretched huge piece of equipment, in my small home. And why I should even need it, if my current ashp it's meant to replace doesn't have one. And how I can navigate this stumbling block in my discussion with Vaillant; whether I can either do without it, or 'barter' some smaller type.
 

And lastly (& to a far lesser degree, reluctantly, & only if this helps me navigate any part of the discussion with them about this stumbling block).. what on earth the bloody thing is.

 

Thanks, Zoot

Edited August 28, 2023 by zoothorn

[zoothorn]

@TonyT I gave some form of vessel above my cylinder here. It's about 1.5 basketballs in size. White, a tank.

 

Is this a 'buffer'??

 

 

 

 

 

 

[zoothorn]

How can I forget about this buffer, when it's the sole/ the only thing I'm asking about on the thread?
 

I'm completely baffled by this question.

[Temp]

10 hours ago, zoothorn said:

The idea refused in an email later, because it needs to be in an insulated place was their reason

 

Tell them if they put it in the loft you will insulate at rafter level. You could always just put a box of insulation over it instead.

Edited August 28, 2023 by Temp

[sharpener]

12 minutes ago, zoothorn said:

@TonyT I gave some form of vessel above my cylinder here. It's about 1.5 basketballs in size. White, a tank.

 

Is this a 'buffer'??

 

 

 

 

 

 

 

No it is an expansion vessel.

[zoothorn]

3 minutes ago, Temp said:

 

Tell them if they put it in the loft you will insulate at rafter level. 

Hi Temp. Thank goodness- this is an idea that I had thought of, but Im so caffufled with this thread I had forgotten it (I almost can't cope anymore on here, it's not doing my health good as Im getting even more stressed, seemingly getting nowhere).

 

Yes. This idea came to me in a eureka moment on a walk. Totally forgot. This idea though, involves a week's work for me in horrible cramped mice ridden loft. SO.. it's a last resort idea.

 

I need desperately to ask though: if there are any other ideas, anyone can think of, before I offer to do this building work for Vaillant to accomodate this f******g huge thing Ive no f******g idea what it even is.

 

Thanks, that is a helpful suggestion. I need to destress & come back tmrw. Zoot

[zoothorn]

2 minutes ago, sharpener said:

 

No it is an expansion vessel.

Urgh.

 

No, I thought it wasn't likely a buffer. But its a white flaming bloody tank that holds presumably, water, which is presumably, what this white f*****g buffer tank also holds too. 

[TonyT]

A buffer will have more connections.

[Beelbeebub]

15 hours ago, zoothorn said:

you might find this odd, but I have no interest in actually using the ASHP for C.heating. It's so ineffective, that I had to ask them how to increace the flow temp/ & some other temp, to even then just get 1 mildy warm room as a result: a room just built & bang up to date insulation (all signed of by BCO) = far too expensive to be useable here.

 

But I can't tell them this. Or they might say "well your house ain't suitable [it isn't] so our offer is rescinded".

 

I only agreed to the system, for a new boiler. No other reason whatsoever; I knew 100% contrary to what the Govt Grant chap told me, that this cottage -wouldn't ever- be warm with this system. No fkn way. "Oh you'll be cosy.." he said etc (he merely had a number/ criteria to fill to get his job done & I was simply a convenient house to call at). My boiler was mouse-ridden & decrepit you see, the whole cottage terribly in need of renovating etc. So how could I dismiss a chance of a free new boiler? If it had an ashp box & new rads too.. these would/ could only ever be superflous & unused.

Can i get this clear? 

 

You had a gas/oil/lpf boiler that was knackered. 

 

You had (on some sort of scheme I assume) the  chance to have it replaced and have an ASHP installed as well

You are complaining that the ASHP installed (a split unit) is noisy inside and vaillant will replace with a monoblock but insist on putting a large buffer unit inside. 

 

The stress of the situation is causing you ill health. 

 

If you don't intend to use the ASHP, and have a boiler, why not just turn the ASHP off?

 

It'll be super quiet then, no big buffer required, not extra.work?

 

Why put yourself thorough stress to install a thing you don't want to use? 

[joe90]

“What is a buffer tank for?”

https://www.kingspan.com/gb/en/knowledge-articles/do-i-need-buffer-tank/#:~:text=A buffer tank is simply,energy from the heat pump.

 

A buffer tank is simply an insulated vessel that adds additional volume of hot water to your heating system, i.e. the water that goes around the radiators and is treated with chemicals to stop rust. It acts a little like a battery for the heating system, allowing it to store more of the energy from the heat pump.

 

 

Do I need an expansion tank and a buffer tank?

 

 

 

 

An expansion tank allows for the expansion and contraction of a system when it heats up and cools off and provides head pressure for the circulation pump. A buffer tank adds volume to a heating or cooling system and helps prevent 

 

the internet can answer nearly all your questions zoot!

 

Edited August 29, 2023 by joe90

[zoothorn]

1 hour ago, Beelbeebub said:

Can i get this clear? 

 

You had a gas/oil/lpf boiler that was knackered. 

 

You had (on some sort of scheme I assume) the  chance to have it replaced and have an ASHP installed as well

 

You are complaining that the ASHP installed (a split unit) is noisy inside and vaillant will replace with a monoblock but insist on putting a large buffer unit inside. 

 

The stress of the situation is causing you ill health. 

 

If you don't intend to use the ASHP, and have a boiler, why not just turn the ASHP off?

 

It'll be super quiet then, no big buffer required, not extra.work?

 

Why put yourself thorough stress to install a thing you don't want to use? 

Hi BeelB..

 

spot on, all of that- & thanks for engaging in my dilemma fully to have written this post.

 

All correct apart from: if I could have turned off the ashp, & just kept the boiler on, I would have done so. The whole system only has 1 big red 'scary' plastic round switch though. Not a separate one for just the CH.

 

With respect though, this is only an option I could have done (if indeed I did find such a separate switch) with the ashp which is to be removed. So whether or not I did isolate the CH/ turn off/ slept ok... it's not applicable, now.

 

I'm simply at the stage of the new system fitting. Which won't have the bedroom interruptions because the pump is in the outside fan unit in a monoblock system. So this noise aspect is water under the bridge THANK GOD (it having been my no.1 problem).

 

I'm still stuck at this buffer hurdle. Simply & only this. Where/ why/ what is it/ how can any small house be expected to accomodate such a huge thing/ why wasn't I told of it when I was planning the position for the new ashp hardware/ what can yiu think of to help me navigate the conversation with head office, to either minimise it's size.. do without it entirely.. or anything/ anything/ anything on god's earth to help me.

 

Thanks, Zoothorn